Hey all, recently took ownership of a lovely Mk6 ST150 that had been sitting for a little while due to being owned by a sadly deceased previous owner.

I'm trying to get it running perfect & for the most part it's sweet as a nut, gearbox was stiff but now fine after 3-400 miles of usage.

It's had all the usual servicing, fluids, filters etc. But I've had a weird issue i (amateur hobbyist mechanic) can't quite put my finger on.

Pulling away slowly is hard without more revs than should be needed (2-2.5k). Otherwise it'll try to stall.

In reverse it pulses the revs and is especially hard to reverse uphill slowly as it wants revs to keep going.

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I've tried the following.

1. New Air Filter
2. New Hoses
3. Checked for obstructions in airbox
4. Pulled plugs, found a dead one (Missing lower pointy part the spark would arc to), replaced all with NGK Iridiums
5. Replaced Ignition Leads
6. Replaced Coil Pack

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As mentioned it runs really nice & pulls lovely on the motorway / normal roads once moving.

Any ideas would be greatly appreciated!

Thanks :)

Throttle body clean and relearn would be a good next step.

I had one of these at 8 years old that I never could get to idle properly though.  Revs would keep bouncing at lights and people thought I wanted a drag race!  

Yep, throttle bodies are a nightmare on these

I added an additional engine earth from the cylinder head lifting eye bolts to the body on mine too and that helped smooth the idle out

There was a hell of a lot of cost cutting on that car

Make sure catalyst is good too, one of mine had terrible performance and it ended up being the catalyst had broken up inside, restricting gasflow

"Grumbly Idle, missing a beat at low speeds, esp. in reverse".

That sounds like me !

How is the fuel consumption ?  Blocked exhaust as Dave suggests, or possibly even sticky brakes ?  Is this drums on the back ?

Depending on whereabouts in Wiltshire you live, if you cannot find a solution, you could talk to Richard at Tremona Garage in Southampton.

19 minutes ago, Paulkp said:

Is this drums on the back ?

There wasn't that much cost cutting!   ST was the only Mk6 to get disc rears.

35 minutes ago, Paulkp said:

"Grumbly Idle, missing a beat at low speeds, esp. in reverse".

That sounds like me !

How is the fuel consumption ?  Blocked exhaust as Dave suggests, or possibly even sticky brakes ?  Is this drums on the back ?

Depending on whereabouts in Wiltshire you live, if you cannot find a solution, you could talk to Richard at Tremona Garage in Southampton.

30mpg on Motorways, 25mpg around town, 20mpg when booting it.

40 minutes ago, DaveT70 said:

Yep, throttle bodies are a nightmare on these

I added an additional engine earth from the cylinder head lifting eye bolts to the body on mine too and that helped smooth the idle out

There was a hell of a lot of cost cutting on that car

Make sure catalyst is good too, one of mine had terrible performance and it ended up being the catalyst had broken up inside, restricting gasflow

Ok i can probably look into the clean and relearn myself. How would i check the cat?

36 minutes ago, TomsFocus said:

There wasn't that much cost cutting!   ST was the only Mk6 to get disc rears.

There was loads.

Developed as EuroIII Emissions then thrown into Euro IV a month before launch, that really didn't help, it was strangled

Removed coil on plug ignition and VVT from engine

Cheap catalyst stuck halfway under the body which never got hot

Rear axle spacers costed out so it always tramlined

PAS cooling system left unmodified so it cooked the fluid

Gearbox weak

Etc Etc

24 minutes ago, AaronReeve said:

How would i check the cat?

Flow test the exhaust or cut the pipe to look at it

2 minutes ago, DaveT70 said:

There was loads.

Developed as EuroIII Emissions then thrown into Euro IV a month before launch, that really didn't help, it was strangled

Removed coil on plug ignition and VVT from engine

Cheap catalyst stuck halfway under the body which never got hot

Rear axle spacers costed out so it always tramlined

PAS cooling system left unmodified so it cooked the fluid

Gearbox weak

Etc Etc

Yes, but it did at least get rear disc brakes!  

In fairness, some of that wasn't about cost cutting or emissions.  The cat and downpipe were deliberately restrictive to keep it under 150bhp for a cheaper insurance bracket to make it accessible to younger drivers.  The IB5 was always weak but just more stressed on those.  I'm not sure they ever considered any other 'box?  MTX75 would probably have been stronger, though it would have required different mounts.

The thing that really ruined it for me was the wheels.  Too big & too heavy.  Didn't add to the looks or the handling.  Slowed the pull away time.  If I'd kept mine long term, I'd probably have swapped a set of 16's on instead.

I've seen a lot of posts saying to clean the throttle body and relearn. And some saying to pull the KAM fuse rather than jumping the terminals with neg disconnected?

 

Which is the KAM fuse?

12 minutes ago, AaronReeve said:

Which is the KAM fuse?

I think it's F16.  There's a fuse diagram on the back of the glovebox but it doesn't give detailed descriptions unfortunately.